Project description:Bdellovibrio bacteriovorus is a Gram-negative bacterium that is a pathogen of other Gram-negative bacteria, including many bacteria which are pathogens of humans, animals and plants. As such Bdellovibrio has potential as a biocontrol agent, or living antibiotic. B. bacteriovorus HD100 has a large genome and it is not yet known which of it encodes the molecular machinery and genetic control of predatory processes. We have tried to fill this knowledge-gap using mixtures of predator and prey mRNAs to monitor changes in Bdellovibrio gene expression at a timepoint of early-stage prey infection and prey killing in comparison to control cultures of predator and prey alone and also in comparison to Bdellovibrio growing axenically (in a prey-or host independent “HI” manner) on artificial media containing peptone and tryptone. From this we have highlighted genes of the early predatosome with predicted roles in prey killing and digestion and have gained insights into possible regulatory mechanisms as Bdellovibrio enter and establish within the prey bdelloplast. Approximately seven percent of all Bdellovibrio genes were significantly up-regulated at 30 minutes of infection- but not in HI growth- implicating the role of these genes in prey digestion. Five percent were down-regulated significantly, implicating their role in free-swimming, attack-phase physiology. This study gives the first post- genomic insight into the predatory process and reveals some of the important genes that Bdellovibrio expresses inside the prey bacterium during the initial attack. Keywords: Transcriptional analysis
Project description:Bdellovibrio bacteriovorus is a Gram-negative bacterium that is a pathogen of other Gram-negative bacteria, including many bacteria which are pathogens of humans, animals and plants. As such Bdellovibrio has potential as a biocontrol agent, or living antibiotic. B. bacteriovorus HD100 has a large genome and it is not yet known which of it encodes the molecular machinery and genetic control of predatory processes. We have tried to fill this knowledge-gap using mixtures of predator and prey mRNAs to monitor changes in Bdellovibrio gene expression at a timepoint of early-stage prey infection and prey killing in comparison to control cultures of predator and prey alone and also in comparison to Bdellovibrio growing axenically (in a prey-or host independent âHIâ manner) on artificial media containing peptone and tryptone. From this we have highlighted genes of the early predatosome with predicted roles in prey killing and digestion and have gained insights into possible regulatory mechanisms as Bdellovibrio enter and establish within the prey bdelloplast. Approximately seven percent of all Bdellovibrio genes were significantly up-regulated at 30 minutes of infection- but not in HI growth- implicating the role of these genes in prey digestion. Five percent were down-regulated significantly, implicating their role in free-swimming, attack-phase physiology. This study gives the first post- genomic insight into the predatory process and reveals some of the important genes that Bdellovibrio expresses inside the prey bacterium during the initial attack. Keywords: Transcriptional analysis 3 replicates of attack phase cells and 3 replicates of 30 minutes post-infection cells were analysed on individual arrays. Replicate 3 was normalized separately.
Project description:Indole is an intercellular and interkingdom signaling molecule, which is widespread in diverse ecological niches. Caenorhabditis elegans is a bacterivorous nematode living in soil and compost environments and a useful model host for the study of host-microbe interactions. While various bacteria and some plants produce a large quantity of extracellular indole, little is known about the effects of indole, its derivatives, and indole-producing bacteria on behaviors in C. elegans and animals. Here, we show that C. elegans senses and moves toward indole and indole-producing bacteria, such as Escherichia coli, Shigella boydii, Providencia stuartii, and Klebsiella oxytoca, while avoids non-indole producing pathogenic bacteria. It was also found that indole-producing bacteria and non-indole-producing bacteria exert divergent effects on egg-laying behavior of C. elegans via indole. In addition, various indole derivatives also modulate chemotaxis, egg-laying behavior, and survival of C. elegans. In contrast, indole at a high concentration to kill C. elegans that has the ability to detoxify indole via oxidation and glucosylation, indicating predator-prey interactions via a double-edged molecule indole. Transcriptional analysis showed that indole markedly up-regulated gene expression of cytochrome P450 family, UDP-glucuronosyltransferase, glutathione S-transferase, which explained well the modification of indole in C. elegans, while down-regulated expression of collagen genes and F-box genes. Our findings suggest that indole and its derivatives are important interkingdom signaling molecules in bacteria-nematode interactions.
2019-08-31 | GSE86312 | GEO
Project description:Predator-prey interactions between Cystobacter ferrugineus and Pseudomonas putida
Project description:This is the reduced model described in the article:
A synthetic Escherichia coli predator–prey ecosystem
Balagaddé FK, Song H, Ozaki J, Collins CH, Barnet M, Arnold FH, Quake SR, You L.Mol Syst Biol. 2008;4:187. Epub 2008 Apr 15. PMID: 18414488; DOI:10.1038/msb.2008.24
Abstract:
We have constructed a synthetic ecosystem consisting of two Escherichia coli populations, which communicate bi-directionally through quorum sensing and regulate each other's gene expression and survival via engineered gene circuits. Our synthetic ecosystem resembles canonical predator–prey systems in terms of logic and dynamics. The predator cells kill the prey by inducing expression of a killer protein in the prey, while the prey rescue the predators by eliciting expression of an antidote protein in the predator. Extinction, coexistence and oscillatory dynamics of the predator and prey populations are possible depending on the operating conditions as experimentally validated by long-term culturing of the system in microchemostats. A simple mathematical model is developed to capture these system dynamics. Coherent interplay between experiments and mathematical analysis enables exploration of the dynamics of interacting populations in a predictable manner.
In the article the cell density is given in per 103 cells per microlitre. To evade a conversion factor in the SBML implementation, the unit for the cell densities was just left the same as for the AHLs A and A2 (nM).
This model originates from BioModels Database: A Database of Annotated Published Models (http://www.ebi.ac.uk/biomodels/). It is copyright (c) 2005-2012 The BioModels.net Team.
For more information see the terms of use.
To cite BioModels Database, please use: Li C, Donizelli M, Rodriguez N, Dharuri H, Endler L, Chelliah V, Li L, He E, Henry A, Stefan MI, Snoep JL, Hucka M, Le Novère N, Laibe C (2010) BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. BMC Syst Biol., 4:92.
Project description:The experimental project studied a MIDAS adhesin minus mutant of predatory bacterium B. bacteriovorus.The predatory bacterium normally invades and lives inside E.coli bacteria, rounding them up to form a two-bacterial structure, called a bdelloplast, and killing the E.coli from the inside. However the MIDAS mutant predator failed to invade in 10% of cases due to one of its (many) attachment/invasion mechanisms being absent. We enriched and purified the 10% of bdelloplasts which did not have an invaded predator inside, by Percoll gradient centrifugation. Although these bdelloplasts did not have an invaded predator they were still rounded and dead. We sent the bdelloplast sample for total protein content analysis at the Oxford Advanced Proteomics Facility. We found that although the bdelloplasts areE.coli cells they also contain secreted Bdellovibrio proteins that normally an invading wild type Bdellovibrio is known to secrete into their prey, during invasion. This suggests that a short-lived failed attachment allowed the Bdellovibrio to secrete in predatory proteins , even though it failed to enter the E.coli, and that those predatory proteins alone were enough to round and kill it.
Project description:An animal’s ability to effectively capture prey and defend against predators is pivotal to its survival1. A key innovation in many predator-prey interactions is venom, which consists of many toxin proteins that shape its phenotype2. Its unusually direct relationship of gene-toxin-phenotype make it an appealing system for studies at the organismal level 3,4. In this work we use the sea anemone Nematostella vectensis as a model organism as it provides us with the opportunity to test for the first time how toxin-genotypes impact predator-prey interactions. Specifically, we compare a native-population5 and a transgenic line which both have significantly reduced levels of Nv1, the major toxin in adult Nematostella6, to animals with wildtype levels of Nv1. We demonstrate that the transgenic strain phenocopies native anemones lacking Nv1 as they both have impaired ability to defend themselves against grass shrimp, a native predator. Mummichog killifish, unexpectedly are attracted to Nematostella with wildtype-levels of Nv1, highlighting that Nv1 plays a complex role in shaping interspecific-interactions. Finally, we demonstrate an evolutionary tradeoff as the reduction of Nv1 levels causes faster growth and increased reproductive rates compared to Nematostella control lines. Overall, our results experimentally link organism’s venom to its physiology, reproduction and interspecific interactions.
Project description:An animal’s ability to effectively capture prey and defend against predators is pivotal to its survival1. A key innovation in many predator-prey interactions is venom, which consists of many toxin proteins that shape its phenotype2. Its unusually direct relationship of gene-toxin-phenotype make it an appealing system for studies at the organismal level 3,4. In this work we use the sea anemone Nematostella vectensis as a model organism as it provides us with the opportunity to test for the first time how toxin-genotypes impact predator-prey interactions. Specifically, we compare a native-population5 and a transgenic line which both have significantly reduced levels of Nv1, the major toxin in adult Nematostella6, to animals with wildtype levels of Nv1. We demonstrate that the transgenic strain phenocopies native anemones lacking Nv1 as they both have impaired ability to defend themselves against grass shrimp, a native predator. Mummichog killifish, unexpectedly are attracted to Nematostella with wildtype-levels of Nv1, highlighting that Nv1 plays a complex role in shaping interspecific-interactions. Finally, we demonstrate an evolutionary tradeoff as the reduction of Nv1 levels causes faster growth and increased reproductive rates compared to Nematostella control lines. Overall, our results experimentally link organism’s venom to its physiology, reproduction and interspecific interactions.